Rivet feeding attachment



May 9, 1950 vo. R. PERRY 2,507,047

RIVET FEEDING ATTACHMENT Q 15. I INVENTOR.

056,42 Z ee/ May 9, 1950 -o. R. PERRY 2,507,047

RIVE'T FEEDING ATTACHMENT."

Filed May 2, 1944 3 Sheet's-Sheet 5 IN V EN TOR.

ateniecl May 1950 UNITED RIVET FEEDING ATTACI-MENT Oscar R. Perry, Inglewood, Calif., assignor to Douglas Aircraft Company, Inc., Santa Monica,

Calif.

Application May 2, 1944, Serial No. 533,811

(Cl. 7S-48) 4 Claims.

This invention relates to an attachment designed to be applied to pneumatic tools operating to drive small headed parts such as rivets or screws, for the purpose of supplying such small parts automatically to the tool in a simple and efficient manner.

The invention has for its general object to apply improved magazine feeding to tools of the kind described, particularly those designed for hand use, though the invention is not necessarily so restricted.

An object of the invention is to provide a part feeding attachment which may be fitted to the pneumatic tool without requiring any modification or structural changes in the tool.

A further object of the invention is to provide a part feeding attachment for pneumatic tools which can be applied to a variety of tools of the kind described.

Yet another object of the invention is to provide a part feeding attachment comprising a number of separate fittings` enabling a variety of different arrangements to be set up.

Still another object of the invention is to provide a part feeding attachment which enables the tool operator to work much faster yet with less effort than when using a tool not fitted with the attachment.

A still further object of the invention is to provide a part feeding attachment for pneumatic tools so arranged that a transfer member moves away from position in front of the operating member of the tool previously to commencement of operation of the driving member of the tool so that the transfer member will not be damaged by the operating member of the tool if pressure air is inadvertently admitted to the tool.

Yet another object of the invention is to provide a part feeding attachment for pneumatic tools which will operate to supply parts to the tool regardless of the position in which the tool is held, thus facilitating the driving of rivets. screws, and the like into work over the head of the operator.

Further objects and features of the invention may hereinafter appear in the following description and/or accompanying drawings in which preferred forms of the invention are given by way of example only. However, it is to be understood that the invention is not in any way limited by this illustrative showing but only as dened by the scope of the appended claims.

v In the accompanying drawings:

Figure l is a partial view of a rivet gun and one form of attachment showing the attachment in position over the end of the set and holding av rivet to be inserted, a shield over the end of the gun being shown in section.

Figure 2 is a front view of the gun shown in Figure l.

Figure 3 is a view in side elevation of the rivet gun partially shown in Figure l with the attachment in retracted position leaving the rivet set free to drive the rivet.

Figure 4 is a cross section on the line 4 4 of Figure 3.

Figure 5 is a cross section on the line 5--5 of Figure 3.

Figure 6 is a perspective view to an enlarged scale of the parts loading attachment.

Figure 7 is a detail view from beneath showing the slide return arresting mechanism mounted on the underside of the attaching bracket, in the operative position of the parts when the slide is moved fully backward, toward the handle.

Figure 8 is a detail view from beneath showing the parts of Figure '7 in their relative positions when the slide has moved partly toward the forward position.

Figure 9 is a detail vieW from beneath showing the parts of Figure 7 in their relative positions when the slide has moved to its fully forward position.

Figure l0 is a side view of a rivet gun arranged for driving ush head rivets and fitted with an. other form of the rivet feeding attachment of my invention, the gun being shown in operating position.

Figure l1 is cross section on the median line of the forward part of the rivet gun shown in Figure 10 but with the parts in the position assumed when a rivet has been brought into position to be inserted in a rivet hole.

Figure 12 is a detail view of a detent arrangement between the pull handle of the attachment and the attaching bracket, the parts being shown in the position of Figure l0, the View being taken from below.

Figure 13 shows the position of the parts of the detent arrangement in the position assumed with the rivet gun in the arrested return position.

Figure 14 shows the position of the detent parts when the part to Ibe driven has been brought into position to be inserted into the work preliminary to operating the gun.

Figure 15 is a fragmentary View showing the forward end of a pneumatic screw driver fitted with the attachment, the tool :being shown in the operating condition.

Figure 16 is a similar View to Figure 15 showing the tool in inoperative condition with a screw held in position to be inserted in the work previous to being driven home.

The attachment is herein particularly described and illustrated as applied to a pneumatic hand riveting tool with trigger air control but it is to be understood that the attachment is not necessarily limited to this type of tool. For instance, it 'may be applied to pneumatic screw drivers, and, with suitable modication of the part gripped by the operator and connections to the operative mechanism, to tools having handles of diiferent configuration and control members of various types for the tool.

The riveting tool shown in Figures 1-9 has an offset pistol handle with a press studin trigger location for controlling the admission of pressure air. rIhe standard tool is furnished with a set retainer spring tted on the end of the barrel.

Referring new to Figure 3 of the drawings, I indicates the pistol gripr handle, l2 the barrel, I4. the exhaust cover ring, l the push button air control trigger, and it the pressure air hose connection of a pneumatic rivet gun, which, as before stated, is left structurally unchanged when using the attachment.

The attachment comprises a bracket member 2l]r clamped on therbarrel l2 of the gun and guiding a slide 22 provided with a bore 24 through which the. set 2S works and with a second bore 28 closely adjacent thereto and serving as a tubular guide to which the rivets to be driven are delivered. A transfer member 3U carries the rivets one at a time from the open end of bore 28 .into position to be inserted in.. a rivet hole and thereafter upset by the set. The. transfer member in the described embodiment is manually operated. Separate attachments Vare provided. to supply power to move the rivets to thebore 28 and to hold. a supply of rivets. These attachments can be used in various combinations as will be more fully explained. hereinafter.

The .bracket member is formed so that it may Ibe. readily clamped uponthe gun barrel as forinstance by. being slotted and clamped ori-the gun barrel by screws 32 passing through bores in. one half and engaging in threaded bores in theother half. A guide arm 34 projects forwardly and is shaped to t into grooves in the slide 22and guide the slide in its reciprocatory motion. The bracket member 2G is provided with a bore for the passage of a pull rod-'36 whichl is screwed at its forward end into a connecting part 3S received in avboreill of the slide 22,I while .at its rearward end the member is riveted to a hand grip 42 which lies in position to. engage andv depress the stud trigger I6 when the. pull rod is fully retracted by the hand grip.

rIEhe slide 22 is pressed outwardly by a spiral spring 44 surrounding rod 3S between the rear vertical face of the slide and the rear wall 41Y of. a bore 46 in the bracket which receives the other endof the spring.

'Ilhe slide is prevented from leaving the guide by engagement of a stud 48 screwed into the arm34 and projecting into a groove 50 inY the lower face of the slide.

A connection 52 forone endof a tubular magazine 54 is arranged to project from the side face of the slide on the side .opposite the transfer member shown in Figures 2 and 4.

The ,transfer member 3S is pivoted at 55cm a headed stud held in an opening in slide 22 and is provided with an end shaped to lie against the outer end face 23 of the slide over the arcuate end face thereof. Member 33 is normally pressed upwardly 4by a wire spring 58 wound around stud 6o and taking into a tubular lug E2 pressed from the side face of the transfer member at one end, and against a suitable abutment at the other end.

The transfer member 30 comprises two operative portions, one 36a., being formed to provide spring ngers to receive and grip a rivet by the shank, and a portion 30h, serving to mask the bore 28 'when the part 33a is moved upwardly away from the bore 28. I prefer to form spring fingers by slotting the face of part 36a and forming the metal to provide a depression to receive the head of the rivet or other part and a slot 30e (Figure 2) through which the shank of the -rivets project.

The transfer member is operated through a crank arm 56 which is operated by the operating member through a stud 68 engaging in slot 10- in the crank arm, passing through a slot 'l2 in the side of the slide, and screwed into the connecting pieceV 3,8 fitted in bore 4'3 in the slide.

The piece 3B is preferably held against rotation in the. bore in any suitable manner and is provided with an internallyy threaded bore into which the pull rod 36 is screwed.

In order toenable the operator to be able toA give further blows after having stopped the operation of the tool. to finish upsetting a rivet, should this be necessary as very frequently occurs, without moving the transfer member, I pro: vide a rest position intermediate the operating and full release positions of the hand grip.

For this purpose I provide an auxiliary trigger 18 mounted on the main hand grip 42 and formed as a straight piece passing through a bore in the vertical front portion 42aA and back portion 42h of the. bend at the upper portion of the grip. The rear end of the member 1 8 is bent into an actuating part 18a arranged between the hand grip.y

42 and the trigger ofthe gun and a finger piece 'i9 is formed to project laterally from the member 18; between the front of the vertical portion; 42a and the bracket ,29. The length of the member 18 is such that, while the trigger can be operated by it in thek partly returned position of thehand grip,.the,member 18 cannot `operate the trigger in the, fully released position of the, hand grip 42 since the vfinger piece 79 will thenV havebeen-moved forward bythe front of vertical portion 42 and the auxiliary trigger is therefore held in inoperative position. The forward end ofv the member '18, is received in a bore 80 in bracket 2U.

While I mayprovide adetent to momentarily arrest return of.. the slide. toits full forward position. during such a supplementary operation.A of., the gun or to give the operator-time to with-Y draw the gun from the worksumciently to ensure that the shank of a rivet ,being moved into posi.-

tion does not strike the face of theV work andv so. get. tilted in the .spring fingers, I prefer to provide. a positive arresting mechanism so that even if theoperator releases `his grasp of the hand grip 42, the slide 22 will be held against movement by spring 44 until the operator again pulls the grip slightly rearwardly to free the Slide from the arresting mechanism, after which the slide and transfer member. Sitcan complete its movement. Anysuitable form of arresting means may be provided, that shown in connection with the form of the Vattachment shown in Figuresl l.

and 2 being shown in detail in Figures 7, 8, and 9. 'I'his mechanism comprises a link 82 pivoted at its forward end to the slide 22 by a stud 83 and having a peg-like projection 84 extending from the under surface of its opposite end. A spring 81 arranged in slide 22 bears against the side of link 82 and acts to urge the link and projection 84 toward one side of the cam groove. The peg 84 engages in a cam groove 85 formed in a plate 86 fitted in a recess afforded by undercutting the bottom of the bracket 2D. A pawl 88 is arranged to extend across the groove and is pivoted by a pin 89 extending into the plate. The pawl is held resiliently pressed against the opposite edges of the cam groove plate by a pin 90 passing through an opening under the pawl 88 into a bore 92 in which a small spiral spring 94 is arranged to bear against the pin, the other end of the bore being closed by a threaded plug 86. The cam groove is formed to provide a straight path for the peg 84 when the slide is pulled back by the hand grip 42 to engage the trigger I6 to operate the tool. During this movement the nose 95 of the pawl 83 is swung aside by the peg 84, against the effort of spring 94.

" The pawl swings back under the influence of the spring 94 to close the path behind the peg and prevents it from returning along the same path. When the operator releases the hand grip to cut oif air from the tool, the spring 44 moves the slide arm, and therefore the link 82, away from the bracket 2l), the peg 84 traveling along the side of the pawl and pushing its way between tail 91 of the pawl and the adjacent wall of the recess in bracket 26 until arrested by a reverse turn 99 in the groove, where it will rest until released by a slight pull on the grip 42 which enables the peg to clear a projection 95 forming this reverse turn of the groove due to action of spring 81 and enables the slide to complete its forward movement when the grip 42 is fully released. During the rest position of the parts, even if the operator completely releases hand grip 42, the transfer member is held against completing its transfer movement under the effort of spring 58 f by the engagement of the lower end of the crank arm with a short track formed by the upper face of a plate screwed to the bracket end of supporting arm 34. The end of the crank arm is swung above the track by the pull rod 36 at the commencement of the rearward travel of the hand grip 42 (see Figure 1). The arresting mechanism could, of course, be arranged on an extension of the hand pull, in which case the transfer member could be prevented from completing its transfer movement by the connection between the hand grip and the transfer member.

When the operator exerts a pull on the hand grip the pull rod first acts on the crank arm, rotating it backward against the resistance of spring 58 until the pin S engages the rear end of the slot 12. At this point the end of the crank arm is in position to clear the face of the track |02 .but is not brought over the track until the slide has commenced its backward movement and just before it reaches a point in the travel of the slide corresponding to the arrest position. Continued rearward movement of the slide takes place until the hand grip 42 depresses the trigger I6 and causes operation of the tool.

The exhaust air is trapped by the magazine loading part |03 which is arranged to clamp on the rearward end of the barrel of the gun and ts closely over the exhaust cover ring I4. The part |03 (Figure 6) may have dierent congurations onto arm 34 and formed to provide clearance foradapted to t over the exhaust rings of different forms of rivet gun, the form here disclosed being adapted to lit over an exhaust ring having a horizontal periphery. The part |03 may be formed in two parts, |B3a, and |03b. Part ||l3a is provided with a divided ring |04 clamped on the barrel by a tightening screw |05. A base portion |08 is carried by one part of the divided ring and is furnished with tapped bores for attachment of part |0317 and with a passage I i6 to lead lair from the exhaust orifice to the outlet H2 from the part |0311 of the part |53 and to the outlet I3 of loading member. This outlet is preferably formed to provide a readily detachable connection with .the end of the tube magazine 54.

While a tubular magazine looping from theA loading member to the rivet feeding bore in the. slide is illustrated, it may be preferred to use a tubular magazine wound into a number of turns and mounted on the side of the tool, in which case the detachable part of the loading part |03 can be reversed so that the coiled tubular magazine is supported snugly on the tool between the connections to the loading member and to the supply bore in the slide. In order to close the end of the tube a gate I4 is pivoted or otherwise mounted to work in a slot extending across the member |631). In order to prevent parts such as rivets being accidentally loaded into the magazine head first, it is advantageous to provide a cut out of the rivet size to be used in a part i6 which may. be separate and formed as a tubular member having the outer end closed. The part H6 may be threaded and screwed into the member H332) and may be changed if a dii-ferent length of rivet is to be used.

The operative face of the transfer member lies close to the outer face of the slide, but with sucient clearance between part of the transfer member holding a rivet and the outer surface of the end face of the slide to permit the head of a rivet to be slid over the outer face of the slide While the rivet is held in the transfer member 30 and the end of the set 26 is within its bore in the slide. The initial backward movement of the slide will bring the head of the rivet against the operative face of the set and further movement of the slide will carry the transfer member away from the rivet if the latter is held in the rivet hole, or if not so held, will carry the rivet away from the set so that the gun, if accidentally fired without the rivet being properly positioned, cannot lire a rivet from the gun or damage the transfer member.

While I have shown a convenient method of feeding the rivets through a tubular magazine carried on the gun which utilizes the pressure of the air exhausted from the gun, it might be pre-` ferred, particularly when riveting is to be done at a station to which the work is brought, to arrange the magazine as a tube attached to some other suitable supply source which, as well known, may comprise an airtight rivet hopper to which pressure air is admitted through a pipe connecting to the air pressure lines, in which case, of course, the member |63 could be dispensed with, rivets being fed from the hopper by suitable means shank rst to the tube connecting the hopper to the rivet supply bore 28.

A shield not shown is arranged to cover the forward end of the gun but is open at the front to permit movement of the operating parts. This shield may be formed in any convenient manner, for instance as a metal stamping clipping securely asoma? 7 inovingpartsl and "for the movement' of the-forfward endeof'the tubular magazine. The shield enablesan operator to steady the rivet gun'or otherfpneumatic tool but avoid contact With'the moving parts ofthe attachment, the shield also serving to protect these parts from dirt and dust.

It-should be mentioned that in view of the manyfdifferent arrangements' for' exhausting air frompneumatic tools', various'coniigurations of thefloadingeand feeding part, when' this-method of-feedingfrivets is used, may be' ne'cessary'as re qu-iredby the design of the particular type 'of gun to' which the attachment is to be applied, and in' some cases, in which the air is-eirhausted' at a point spaced from the gun, separate exhaust trapping andrivet loading attachments may beitted and operatively connected in any suitable iran'- ner.-

Asshovv'n in Figures y15' and 16', the attachment canvbe used-to feed screws to a pneumatic screw' i driver without modification, the attachment being mounted on the screw driverbarrelV and' adjustedin the'saine manner as when usedk on a rivetinglgnn. The tip of the screwis supported byf entering .itin the work piece or in a previously drilled holeand pushing against it with the 'screw drivel' whichI pushes the head of the screw against the= screwdriver bit HS after which the spring. ngersf-afaredisengaged by the backward niove ment'of slide 22, leaving the end of the screw driver' bit uncovered and engaged in the head of tli'efscrew asshown in Figure 15.

Thefforin of the invention shown in Fi todtinclusive'may be applied to' a riveting gun fcoreitlierflush4 or round head rivets. Since flush' 5:1.

type rivets are driven with a wide mushrooi'n typef set; it is' necessary to use a transfer member Vso formed-"that no operating parts engage against theredges of the wide face ofthe set andthe' transerineinber isaccordingly formed asa strip' of 'meta-l opera-ted' from an end reinote from' the rivet transferring end.

The attachment comprises a bracket i supporting'l a slide |22'on an arm |2 projecting from the bracket-ay pull:A 132 slidably related to the f bracketb'y a' pull rod |23seated in al'bore in the'- bracket'and in the slide, a spring arranged'A bei tween lthe bracket andthe rear vertical wall'f' or 'the slide, a loading part |32, and an arresting! mechanism |34, as inthe form of the invention' previously described. The transfer member fand operatingnrechanism carried by the slide arefarranged between two' side plates l'forming' the sides of the slide and are secured to a brdgefpiecel |385. Thebottom edges of the side plates be slidably secured tothe arm |24 in any suitable manner. rfherivet supplying bore is `arranged in'V afdetachable'block MQ carried on the upper sur# iace of: -the bridgel connecting the side plates andi maybe-'readily changedA to accommodate Vrivets cfdifferent size.

The operating mechanism for ther transfer member comprises a bent lever |42 having. a?

hingeconneotion at itsouter endwith 'ai trans= fer member Ulli. This transfer member is pro'-A videdat its free end with a, rivet receiving slot 8; thebent lever' to'rbtat'e yupwardly` abou-tits pivot'. A'secondspiing ISS-is arranged between the for'-' ward end of thebent lever' and transferelement 5 and acts to hold thiselement against the face of" the rivet` feedingblock |40.

rnc varresting mechanism shown in Figures 12,; iandlle comprises a plate |49 mounted atY the lower end of aforward extension of the pull wriichis-bent to lieparallel to the longitudinal emisor the attachment, and an arm-l' pivoted to the arm |241 and capable of moving in both horiaontall and vvertical planes. A projection |56- is formed at the end of the pivoted arm |60 engaging in a cam groove formed in the plate. A spring |62 mounted inthe supporting arm is arranged tobea-r against'the pivotedvarm to urge it`- into engagement with the bottom suriaceofl t'hcam' groovefand alsoto urge it againstone' side' off saidgl-roove byl engaging over the top. of` the arm and ag'ainsta shoulder |60@- thereon. A path-for the projection isl provided, as in the case ofi tlievcam plate as described with reference to tle'form 'of the' invention shown in Figures 1 and 2," .with astra-ight portion |53 followed by the projection during the backward travel of the poil, andan'"arrestingportion |66 for holding the e against completing its return movement itilfrel'eased by a further slight rearward moveent'of the pull by the' operator from a proje'c- 5;), tron |51 bounding the arresting portion.

in order to force the projection |56 to follow aldi erent path duringthe'return movement of the slide-'toward the-outer end of the supportingfrom that-followedin the movement of the' siA e toward the supporting. bracket, an inclined facedois `arranged toward the'rearward end of the straight-portion |58 of the cam groove, the; paojection'rriding up this incline and engaging over th'een'd wall of the incline' and reentering. thefgroove on completing its travel over the-in-Y cline. Onthe'return movement of the slide the projection' follows along the inside Wall of the groove due to the force exerted by the spring Forwardtravel-of the slide |22 on the arm 52d :limited byVl engagement of a projection |10- withA a stogi-|12 projecting from the slide.- l

Ef thefoperator releases the` pull while-the slide isarrested during its return movement, the transfer member! |44 will be restrained from swinging a'vpart'such as a rivet from the supply passage Mila toward the set because of its connection to the pull 42. Preferablyv al cam surface it 'is-provided onthe uppersurface of the arm |24 a-nd'enga'gesagainst a cam IEB surface 55 onthelower surface of the bent lever to hold th'e'upper end of the transfer memberv with apartsupportedsthereon above the opening of the' supplybore'during the rest position of the-p`arts. vIn'operettion ofthe form of attachment describedw-ithreference'to Figures lO'to 14, the' operator grasps -thehandle of the-"tool and the pul,A moving-.the pull backward until it engagesv and depresses the trigger I6 admitting compressed air into the tool. The rearward move-i ment of' the pull is commuriicatedv through the pull rod to the bent lever which is first drawn' back' from the upward position in which thea partis Vheld in positionl to be inserted in the worklpiece-until the' underside of'theV bent leveren?" gages against the vsupporting arm and prevents further downwardmovement of the lever and transfer-member, in which position the portreceiving opening; is in registry with the open endl of-the part supplying passage. Rearward move-` mentis thereafter transmittedf'to the slide caus# ing it to move backward against the effort of the spring |39 until the fully retracted position is reached. After the driving of the part is completed, the operator releases the pull l2 enabling the slide to again move forward with the bent lever still in its retracted position until the resting position is reached and if it is not necessary to again operate the tool, the operator gives a furthe-r slight backward movement to the pull and then releases his grasp enabling the slide to move forward until the projection il!) engages the stop |12. This full release of the pull permits spring !48 to move the lever and transfer member upwardly, the head of the part carried in the opening yat the upper end ofthe transfer member sliding over the end face of the slide and face ofthe set into the axial line thereof. whereupon the cycle may be repeated.

In operating the usual rivet gun the riveter, if right handed, holds the gun in his right hand and a supply of rivets in his left hand, and when unskilled, concentrates his attention on driving one rivet, then uses his left hand to place a rivet in a rivet hole and then again uses his right hand to drive the rivet. When the riveter becomes skilled he can use both hands simultaneously, placing rivets with his left hand while driving rivets previously placed with the rivet gun held in his right hand, but even when skilled, must divide his attention between placing and driving the rivets.

When using the attachment of my invention the operator concentrates his attention and uses both hands, if required, on driving the rivets and thus can work faster and do better work with less drain on his energy and consequently with much less fatigue.

The attachment also makes working in hard to reach places, or overhead, much simpler and faster since not only can the rivets or other parts be more easily inserted in the work, but the part is held mechanically at all times and therefore cannot drop out of the work before the operator can bring the tool into position against the head of the part.

It is believed that the parts-feeding attachment of my invention provides a valuable advance in the field of pneumatic tools generally, and particularly with relation to pneumatic riveting machines.

I claim:

1. A fastener feeding attachment for stemmedand-headed-fastener driving pneumatic tools that have a barrel, a handle, a driver axially reciprocatable in said barrel, and a compressed air inlet control member carried by the handle, comprising: an attachment bracket mounting the attachment on the barrel of the tool; a member mounted in said bracket for recipro tion substantially parallel to the axis lof said barrel; a pneumatic conduit extending longitudinally of said slide member and opening forwardly t feed fasteners stem first to a point subadjacent the driver: a transfer unit disposed in lengthwise attitude longitudinally under barrel and pivotally mounted at its rear end on said slide member; a biasing member, for urging said transfer unit normally upwardly. interposed between a portion of said unit and an adjacent abutment in the attachment device; a crank arm on the rear portion of said transfer unit: a compression spring operatively interposed between said bracket and said slide member for automatically urging the latter forwardly; a manually operable member disposed adjacent the tool iii handle and operatively so connected with said spring as to enable the spring to urge it forwardly; and a slot in the one end portion of said crank arm and a pin on said manually operable member engaged in said slot to enable said spring to elevate the fastener-carrying end of said transfer unit when the slide member is substantially at its forward limit of movement, thereby to position said fasteners shank first forwardly adjacent the tools driver, and to enable said manually operable member and crank in cooperation to depress said transfer unit when the slide member is at its rearward limit of movement; said manually operable member in its rearward position of movement contacting and operating the member controlling the admission of pressurized air to the tool.

2. A fastener feeding attachment for stemmed.- and-headed fastener driving pneumatic tools that have a barrel, a handle, a driver axially reciprocatable in said barrel, and a compressed air inlet control carried by the handle, comprising: an attachment bracket mounting the attachment on the barrel .of the tool; a slide member mounted in said bracket for reciprocation substantially parallel to the axis of said barrel; a pneumatic conduit extending longitudinally of said slide member and opening forwardly to feed fasteners stem first to a point sub-adjacent the driver; a transfer unit disposed in lengthwise attitude longitudinally under said barrel and pivotally mounted at its rear end on said slide member; a biasing member, for urging said transfer unit normally upwardly, interposed between a portion of said unit and an adjacent abutment in the attachment device; a crank arm on the rear portion of said transfer unit; a compression spring operatively interposed between said bracket and said slide member for automatically urging the latter-forwardly; a manually operable member disposed adjacent the tool handle and operatively so connected with said spring as to -enable the spring to urge it forwardly; and a slot in the one end portion of said crank arm and a pin on said manually operable member engaged in said slot to enable said spring to elevate the fastener-carrying end of said transfer unit when the slide member is substantially at its forward limit of movement, thereby to position said fasteners shank first forwardly adjacent the tools driver, and to enable said manually operable member and crank in cooperation to depress said transfer unit when the slide member is at its rearward limit of movement; said manually operable member in its rearward position of movement contacting and operating the member controlling the admission of pressurized air to the tool; a detent member pivotally mounted on the bottom face of said slide member; camming and stop members complementary to said detent member mounted on the adjacent upper face of said bracket member and correlated with said detent member to cause it to engage said stop and stop movement of the slide and the transfer member carrying therein a part to be driven, thereby to maintain said part out of the way of said driver to enable said tool to be further drivingly operated on an incompletely driven fastener.

3. A self-feeding pneumatic tool for driving stemmed-and-headed fasteners and including a barrel, a handle, a driver axially reciprccatable in said barrel and a compressed air inlet control member carried by the handle, comprising: a support at one side of said barrel; a slide memport and said `slide member for 4automatically urging the latter forwardly; -a'manually operable member disposed adjacent'the tool handle 'and operatively :so connected with `said spring A'asto enable the spring to urge itfcrwardly; and 'a slot'in'the one end portion of said crank 'arm and a pin on said manually operable member engaged in said slot to Ven'altale said spring to elevate the fastener-carrying `end of said transfer unit when the slide memberis substantially at its forward limit of movement, thereby to position said fasteners shank first and forwardly adjacent the tools driver, and to enable said manually operable member and crank, in cooperation, to depress said transfer unit'when the slide member is at its rearward limit of movement; 'said manually operable member, in its rearward position of Y movement contacting and operating the member controlling 'the admission` o'f pressurized air to the tool.

4. A self-'feeding ,pneumatic tool for driving stemmed-and-headed fastenersand including a barrel, a handle,.a driver axially reciprocatable in `said barrel and a `compressedair inlet control member carried by the handle, comprising: a support at one side of said barrel; a slide member mounted in said support .for reciprocation substantially parallel to the axis of said barrel; a pneumatic conduit extending longitudinally of said slide member and opening forwardly to feed fasteners stem first to a point sub-.adjacent the driver; a transfer unit disposed in lengthwise attitude longitudinally beside said barrel and pivotally mounted at its rear end on said slide member; a biasing member, for normally urging said transfer unit upwardly, interposed between arportion of said unit and anadjacent p'ortion'of said. support; a crank armon the rear lportion'of said transfer unit; a compression spring opera- '12 tively interposed between said support land seid 'slide/member "for automatically urging .the i latter forwardly; amanually operable member disposed fadjacentthe tool lhandle and operatively so Vconnectedwith said spring'as to enable the vspring rto'urgeit forwardly; and a slot in the one end portion of said lcrank arm and a pin on said 'manually operable member 4engaged in said slot 'to enablesaidspring to elevatethe fastener-carrying fend o'f `said transfer unit when the slide member-is substantially at its forward limit 'of movement, lthereby vto position said fasteners shank Tfirst and forwardly adjacent the tools driver, and 'to enable said manually operable memberand crank, cooperation, to 'depress 'said `transfer unit'when the slide member isat ltsrearward limit fo'f'm'ovement; Asaid manually operable member, in 'its rearward position 'ci movement-contacting and operating the member Lcontrolling Athe-'admission yof pressurized air to thetool; an elongate'leven having a ldetent pin projecting rectangularly from the face of one end, pivotally mounted on the vbottom face :of said slidemember; a guideway for said pin formed in the adjacent face Io'fsaid bracket and itermi natedatfone end by ka stop member shaped and mounted ifor 'engaging and stopping said pin and stopping forwardmovement of Asaid slide and the transfer member carrying therein a part to be driven thereby to maintain said part out of 'the path of said driver to enable said tool to be'further 'driving'ly operated on an incompletely driven fastener.

GSCAR R. PERRY.

y'REFERENCIES CITED The following references are o record` in the iile fof' tlii's patent:

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